Test Driven Development (TDD) is an approach for developing programs incrementally by first writing tests and then writing enough code to satisfy them. Though there have been some experiments for evaluating TDD on smaller scope, its impact on a larger scope of program development activities needs to be investigated. In this work, we evaluate the impact of TDD on various program development activities like designing, coding, and testing, through a controlled experiment where we compare it with the conventional way of developing the code. In a single-factor block design, two groups of students developed two moderately sized programs following the two development-styles under study. Our results suggest that TDD helps in reducing overall development effort and improving developer?s productivity whereas the code quality seems to be affected by the actual testing efforts applied during a development-style.